It is well known that, in the production of yarn, textile strands are spun on conventional or open-end spinning machines. Also, spun strands and/or continuous filament strands are intertwisted on twisting machines. In such machines, supply strands are directed from supply sources into a row or series of processing units, and the processed strands are delivered to respective take-up means. In this regard, in the case of conventional spinning frames, the supply strands are generally in the form of rovings, and the processing units are in the form of drafting units. In the case of open-end spinning machines, the supply strands are generally in the form of slivers and the processing units generally are in the form of rotor units. In the case of twisters, the supply strands are generally in the form of spun yarns and the processing units are in the form of twister rolls or twister heads.
As set forth in U.S. Pat. No. 3,726,072, issued Apr. 11, 1973 and commonly owned by the assignee of the present application, in order to avoid the occurrence of lap-ups subsequent to the breakage of attenuated or twisted strands issuing from the processing units of a textile yarn forming machine, and to thereby avoid the wasting of stock prepared for yarn formation by delivery of the stock into the usual vacuum collection system rather than as a yarn, and thereby avoid consequent degradation of the quality of yarn produced due to the reworking of waste material, it is important that any broken processed strand be promptly and efficiently detected and that the corresponding supply strand is quickly and effectively interrupted in its course to the respective processing unit. The apparatus and method disclosed and claimed in the aformentioned patent has performed quite well and has been well accepted in the textile industry. That patent discloses the use of a traveling pneumatic cleaner serving as a carrier or carriage for a traveling detector means which monitors a series of processed strands issuing from a series of yarn processing units, such as drafting units, to which respective supply strands pass. Upon detection of a broken processed strand by such detector means, the respective supply strand is interrupted by direction of flowing air from the traveling cleaner to impinge upon and actuate a respective strand interrupting member by displacing the same from a normal or inactive position to an active position such as to engagingly restrain and thus interrupt movement of the respective supply strand into the processing unit.
Since the traveling cleaner and the detector means travel together and an individual supply strand interrupting means is provided for each yarn processing unit, the detector means is positioned so as to lead the projected flow path or "air bullet" of the directed air flow in accordance with the direction of travel of the traveling cleaner, thus providing a minimal response time for effecting the direction of the flowing air upon detection of a broken processed strand, such response time serving to insure that the "air bullet" will impinge on only the properly selected one of the strand interrupting means.
In many installations, the traveling pneumatic cleaners are constructed so that they may move alternatively in either direction, that is, the traveling cleaner may alternately traverse a textile yarn forming machine or a row or rows of such machines in opposite directions, such as in the instance of the traveling cleaner being mounted to travel on a double-ended track, or in the envent that a particular machine or a portion thereof is being repaired by persons whose efficiency might be impaired by the movement of the traveling cleaner past such persons while they are repairing the machine. Since the detector means on the traveling pneumatic cleaner leads the "air bullet" in the aforementioned patent, it can be appreciated that the timing relation between the detector means and the "air bullet" would be reversed if the direction of travel of the traveling cleaner were to be reversed. Stated otherwise, the detection of a broken processed strand by the traversing detector means would occur after the projected path of the directed air flow or "air bullet" had already moved past the supply strand interrupting means which must be actuated for interrupting the desired proper supply strand, and thus the latter supply strand would not be interrupted and a lap-up likely would occur. Also, because of the usual narrow gauge or relatively close proximity of adjacent processing units of yarn processing machines, the directed air flow or "air bullet" might impinge upon and actuate other than the desired strand interrupting member and thus cause unintentional interruption of a supply strand into a processing unit whose processed strand issuing therefrom had not been broken.